Volcanism refers to the eruption of magma or molten rock, or hot water and steam, including volcanoes, pyroclastic fragments, geysers, as well as fumaroles on top of the surface of a planet (Encyclopedia Britannica 1). A volcano refers to the vent through which gases and magma are discharged. When a planet loses its internal heat it results to volcanism. When a rock that is close to the surface becomes hot sufficiently enough to melt, it results to a volcano being formed.
On the Earth, volcanism often occurs in association with plate boundaries. Where two plates move apart, for instance at mid-ocean volcanic ridges, the Earth's interior material rises up slowly. As soon as it reaches lower pressures it melts, and fills in the gap. Subduction of one plate under another may form chambers of magma. These magma bodies feed the volcanic islands that mark subduction zones (The Lunar and Planetary Institute 1).
Volcanism can also occur in the interior of the plate at hotspots even though most volcanic activity occurs at plate boundaries. Hotspots are believed to originate from huge plumes of exceedingly hot material escalating from deep in the interior of Earth. The hot material upsurges slowly, in the end it melts as it reaches lower pressures near the surface of Earth. As soon as the material erupts it produces enormous lava flows of basalt. An example originating from a hotspot is the broad, gentle shield volcanoes of Hawai’i (Volcano World 1).
One of the sites of active volcanism is along the axis of the oceanic ridge system. This is where the plates move away from each other on both sides of the ridge. The magma outpours from the mantle forming new ocean floor along both plates’ trailing edges. Nearly all of this volcanic activity transpires underwater. A small number of places have the oceanic ridges appropriately raised beyond the deep seafloor that they appear from, and sub aerial volcanism ensues. An example is the Iceland. Along the oceanic ridges, the magmas erupted there are composed of basalt.
Even though volcanism is well-known on Earth, there is proof that it has been significant in the advancement of the other terrestrial planets such as Mercury, Venus, as well as Mars, and several natural satellites for instance, Earth’s Moon and Jupiter’s moon Io (Encyclopedia Britannica 2).
The moon, which is the closest neighbor to the earth, has small volcanoes, fissures, as well as far-reaching flows of basalt, a dark volcanic rock which has been finely grained. The huge dark basins that a person is able to see on the Moon are called the Maria. But, all these volcanic features are very old. On the Moon, there are no active volcanic features. Most of the volcanic activity transpired early in the history of the Moon, before approximately three billion years ago. The most current lava flow happened roughly one billion years ago. The dark areas on the Moon are known as Lunar Maria. The Lunar Maria is low, smooth areas of dark, finely grained volcanic rock known as basalt. In 1971, the Apollo fifteen mission collected this rock sample. It is basalt, a category of rock that congeals from volcanic lava. This specific basalt was formed three point three billion years ago (The Lunar and Planetary Institute 2).
The planet Mars has volcanic features that are alike in shape when compared to those on Earth, even though much greater. The Moon has large shield volcanoes, similar to those in Hawai’i, which contain a hundred times extra mass in comparison to those on Earth (Volcano World 3). The Olympus Mons has been the tallest volcano in the solar system. Olympus Mons is twenty-two kilometers tall, matched to Mauna Loa which is nine kilometers tall. Olympus Mons is six hundred kilometers across. Some of the volcanoes on Mars, as well as the Olympus Mons, take place in the Tharsis area; the magma meant for the volcanoes may arise from hot material outpouring in plumes from deep in the inner Mars. Basalt meteorites from Mars point out that volcanism has happened in the past a hundred and eighty million years. There are hardly any impact craters that take place on the Olympus Mons’ lava flows, suggesting that this volcano has most likely erupted in the past few million years.
The planet Venus consists of more than one hundred thousand and seven hundred volcanic features and many of these features still look fresh, that is, un-weathered. Most of Venus’s surface has been enclosed by massive flows of basalt lava, most likely in the past few hundred million years. This blanket of lava totally enclosed the surface features, for example, impact craters. That point that only a small number of craters dot the surface of Venus provides proof of the recent nature of this reemerging (The Lunar and Planetary Institute 3).
Io, which is Jupiter's innermost moon, is the most volcanically active body in our whole solar system. NASA operations imaged enormous plumes shooting more than a hundred of kilometer beyond the surface, walls of fire connected with magma and active lava flows flowing from fissures. The entire Io’s surface is enclosed with lava flows and volcanic centers, which have enclosed all of the Io’s impact craters.
There is a reason why people have not found active volcanoes on all moons and planets. Active volcanoes take place on planets that are still hot. Generally, the bigger the planet, the slower it o takes to cool. Small moons or planets, for example, our Moon and planet Mercury, have cooled to the extent that they are no longer sufficiently hot to liquefy rock. Bigger planets, such as Venus and the Earth, are still hot in addition to that they still have active volcanism (The Lunar and Planetary Institute 4).
Works cited
Encyclopedia Britannica. Volcanism. Encyclopedia Britannica Inc, 2013. Web 4 December
2013.
The Lunar and Planetary Institute. Volcanism. Web 4 December 2013.
Volcano World. Hawaiian Volcanism. volcano.oregonstate.edu, 2013. Web 4 December 2013.
